1. Field of the Invention
This invention is directed to a portable scale particularly adapted for the weighing of persons and particularly adapted for ease of transportation by virtue of its compact size and light weight when not in use.
2. Description of the Prior Art
In affluent societies, man has been concerned with his weight because overindulgence in food can cause overweight together with the problems associated with overweight. Consequently, the need for weight measurement has been recognized. Many different types of weighing scales have been proposed and sold on the market. In quantity, the largest number of scales sold falls into the "bathroom scale" variety where weight causes spring deflection, and the deflection also moves an indicator. This kind of construction is inexpensive and fairly trouble-free so that such scales can be made fairly widely available. When more accuracy is required, beam-balancing scales are used where a scale weight is moved out on balancing beams.
The prior art also includes a number of different kinds of scales which employ hydraulic liquid as the medium interconnecting a movable plunger and the indicator. In this type of structure, the liquid is usually employed as a displacement measuring material to indicate the amount of motion of the platform against a resilient resistance so that the liquid simply serves as an interconnecting displacement signal. One air-filled device (Newman patent, U.S. Pat. No. 3,433,316) is such a device where the air pressure does not serve as resistance to weight, but merely indicates the amount of deflection of the platform on weight-supporting springs.
Additionally, the structures of the prior art are quite complicated because they have equipment which maintain the level character of the platform.
The present invention includes the concept that a light, portable scale can be produced without the need for a structure to maintain the platform parallel to the supporting base and that reading accuracy can be achieved by a properly designed platform, air bag, and pressure-reading device calibrated in weight units.